The purification of glycerol from water by melt layer crystallization with an additional solvent to influence the crystallization kinetics is investigated. Static cold finger experiments including a sweating-like post-treatment were carried out. A simple seeding technique is introduced to facilitate layer crystallization without primary nucleation or agitation. It is shown that the glycerol crystal layers tend to burst in a traditional sweating procedure, but a modified temperature profile allows a post-treatment with a similar effect. The solvent improved the separation efficiency of the growth step and also the one of the sweating step. Therefore, its effect does not only result from its influence on forced convection but also that on natural convection and diffusion.